toString fails with mysterious message due to bug

[guitarvydas]

https://github.com/guitarvydas/cparse/blob/report/insert.html#L59

I created erroneous code and hit a JS error. It would be nicer if toString() were to give a better error message...

I forgot to call the appropriate semantic function, then called .toString().

.toString() failed with "undefined", which did not help to figure out what was wrong...

You should be able to load "insert.html" into a browser and hit the "insert" button. .toString() then fails on the code at line 59.